1. Field of Invention
The invention relates to an installation structure for an electric motor to be installed in a motor vehicle.
2. Description of Related Art
Recent motor vehicles employ electric motors of various types. These electric motors include those employed, for example, as actuators for electronically controlling throttle valves that regulate the amount of air to be drawn into an engine of the motor vehicle. The electric motor is installed in a throttle chamber assembly.
The electric motor is inserted in a cylinder-shaped installation hole formed in a throttle body of the throttle chamber assembly, and is fixed at the opening end of the installation hole with fastenings such as bolts. As the electric motor is supported only at one end, the electric motor will resonate due to vibrations of components such as an engine when the electric motor is used in the vicinity of the components that vigorously vibrate.
The electric motor, used for regulation of the amount of air drawn in, is required to perform control operations with high precision. Therefore, resonance due to the vibrating components such as the engine must be avoided or minimized. To achieve this, as shown in FIG. 8, an electric motor M for operating a throttle valve 10 is installed between a deeply grooved section 12a and a projected section 13a via vibration-proofing members such as an O-ring 14 and a spring. The deeply grooved section 12a is formed indented on a bottom wall 12 of an installation hole 11, and the projected section 13a is formed on the end wall of a casing 13.
In the structure described above, however, the vibration-proofing members, such as the O-ring 14 and the spring, are necessary to support the motor at the second end. This gives rise to a problem in that the number of components increases.
In addition, in the structure described above, the electric motor must be installed by accurately positioning the vibration-proofing members in the bottom wall of the installation hole. When the casing or yoke of the electric motor is inserted in the installation hole, however, the vibration-proofing members are not visible; that is, the installed status of the vibration-proofing members cannot be visually verified. This reduces efficiency and reliability in production. These are problems that must be resolved.
To overcome the problems described above, an object of the invention is to provide an electric motor installation structure, in which a motor yoke is inserted in a cylinder-shaped installation hole, the motor yoke having one open end and one closed end, formed as a cylinder, and installed in the installation hole by fastening on the side of the open end of the motor yoke. An end wall of the motor yoke is spaced from the bottom wall of the installation hole, and flexible tabs are formed to protrude from the end wall of the motor yoke so as to be pressed into contact with the bottom wall. The flexible tabs serve as vibration-proofing members that minimize the effects of resonance due to vibration of the engine. This eliminates the need for vibrationproofing members, such as an O-ring and a spring, substantially reducing the number of components. Furthermore, the use of the tabs eliminates the assembly of the vibration-proofing members, which must be performed by accurately positioning the vibration-proofing members in the bottom wall of the installation hole, thereby improving processing efficiency.
The flexible tabs protruding from the end wall of the motor yoke are formed so as to extend in the axis-rotation direction of the motor casing. This type of formation allows long flexible tabs to be formed even when the diameter of the motor yoke is small, thus increasing reliability.